If you are seeing the green brick/nugget stuck in the progress bar, then it is likely a hardware or driver problem (not an Indigo bug). Do you have the CM11 USB to serial adapter cable plugged directly into your Mac? There are issues with using USB to serial adapters and some USB hubs, so I recommend always plugging it directly into your Mac. The other issue is could be the driver. I recommend using this open source driver for that adapter cable. Folks have reported better success with it than the one Marmitek recommends. I think you are already using that driver though, so I suspect it could be a USB issue.
Regards,
Matt